Grid construction



Dec. 28, 1948. Z, J, ATLEE y 2,457,62

GRID CONSTRUCTION Filed July 5, 1945 His* ill!

@ m MMWX device. or secondary electron emission by the grid may Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE GRID CONSTRUCTION Zed J. Atlee, Elmhurst, Ill., assignor to General Electric X-Ray Corporation, Chicago, Il1.,a 'corporation of New York Application July 3, 1945, Serial No. 603,031 I (Cl. Z50-27.5)

Claims.

tioned frequently include, as a part thereof, a'

grid element for the purpose of controlling electron flow between anode and cathode elements of the device, electrons being emitted from the cathode and passing to the anode under the control of the grid, during the operation of the Under the-circumstances, any primary interfere with the desired control accomplished Aby the grid, particularly where the flow device is "designed or adapted for high voltage operation.

An important object and purpose of the present invention is to provide an improved grid structure for electron ow tubes particularly those employed for high voltage operation; a fur- -ther object being to provide a grid lthat is subformed and arranged to provide a satisfactory grid having adequate mechanical strength@ Another important object is to provide a grid material comprising platinum or beryllium or an alloy embodying both platinum and beryllium f either alone or alloyed with traces of other materials; a further object being to utilize a grid element comprising zirconium carrying a surface filament of zirconium oxide, to form a substantially inert grid.

The foregoing and numerous other important objects, advantages, and inherent functions of the invention will become apparent as the invention is more fully understood from the following description, which, taken in conjunction with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

Fig. 1 is a sectional view through an electron flow device embodying a grid formed in accordance with the teachings of the present invention;

Fig. 2 is a perspective view of the grid;

Fig. 3 is an end view of the grid shown in Fig. 2; and

Fig. 4 is a sectional view taken along the line 4--4 in Fig. 2.

To illustrate the invention, the drawings show a three-element electron flow device I0 comprising a sealed envelope Il, which may be made of glass, an electron emitting cathode I2, an anode I3 spaced from the cathode, and a grid I4 interposed between the anode and. cathode, said anode, cathode and grid being supported within the envelope II.

The device I0 may be operated by energizing the cathode for electron emission and by applying a suitable electrical potential between the anode and the cathode to drive electrons, lemitted by the cathode, to the anode, control of electron flow being accomplished by applying a controlling potential to the grid. The anode, cathode and grid mayjof course, have anyV suitable or preferred form for the purpose of accomplishing their respective functions. As shown, the grid may comprise a cage enclosing the cathode I2, said cage comprising wire I5 arranged in loops supported by spaced apart end members I6 and Il. The. member I6 may comprise a band cf .metal having spaced, dependent lugs I8 integrated therewith and forming a means for mounting the cage on suitable support means within the envelope. The cage member I1 may also' comprise a generally cup-shaped metal member having a central opening I9 and additionally spaced apart openings 20 disposed around the central opening. The Wire I5 may comprise a single strand arranged upon the members I6 and I1 in serpentine fashion forming loops extending therebetween and secured thereto to form a generally tubular cage. Each end of the wire and the several looped portions thereof may be welded, brazed, or otherwise fastened and electrically connected to the members I6 and I1. An additional wire 2I of material similar to that of the wire I5 may be arranged in helical fashion upon the stretches of the wire I5 between the support members I6 and Il, the wire 2l being preferably welded and thus electrically connected with the wire I5 at each crossing thereof.

The grid I4 may be mounted upon and electrically connected to a metal supporting member 22, preferably comprising molybdenum, nickel or steel, which is welded or otherwise connected at one end to the lugs I 8. At its other end, the member 22 may be integrated, as by welding, to a plate 23, which in turn is fastened, in integral fashion, to the bottom of a metallic cup 24 having edges forming a glass-to-metal seal 3 with the ope'n end edges of a preferably re-entrant sleeve portion 21 of the envelope. The grid may be electrically connected in a suitable electrical circuit outwardly of the envelope by means of a metallic stud 3| having a metal head 28,

preferably screw threaded to the stud as by means of a threaded socket 29 in the head, and a threaded stud portion 30 adapted to removably fasten the stud to the head, the head 28 being electrically connected, as by Welding the same to the member 24, which preferably comprises a ferrous material having a high nickel content to render the same readily sealable with the glass envelope. i Y A The upper end of the grid I4 may be mounted on a support stem 32 having a portion extending in the opening I9 to center the grid on the stem. The stem 32 may also form an insulated mounting f-or laments comprising the electron emitting cathode I-2. The cathode may be connected in a'ilament energizing circuit outwardly of the envelope by suitable conductor means extending outwardly through a suitable seal construction 33 at one end of the tube; and the anode I3 likewise may be connected in circuit outwardly of the envelope by means of an electrical conduct- 'ing anode mounting including a stud 34 extendingv outwardly of the envelope through a suitable seal 35. f

In order that the grid I 4 may be constituted i alloy of platinum containing a relatively Small amount of beryllium in quantities of the order of 0.1 per cent, just suiicient to impart adequate strength and rigidity in the grid material.

Exceedingly satisfactory results may be obtained by utilizing zirconium as a substantially inert grid` material, the invention, in this connection, contemplating the employment of a grid comprising zirconium metal, either in pure form or alloyed with traces of platinum or beryllium, or both, the zirconium material being oxidized to form a surface iilm of zirconium oxide, thereby affording a grid structure substantially incapable of electron emission even at high temperature.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction. and arrangement of the though it is not essential, for practical purposes,

'to make the end members of absolutely inert material. The end members consequently may 'compris-e relatively inert material such as molybdenum. The wires I5 and 2I, however, comprise material which is incapable of electron emission.

vor alloys including platinum or beryllium, particularlyA the alloy of platinum and beryllium. More specifically, the preferred material is an several parts without departing from the spirit lor scope of the invention, orY sacrificing any of its attendantadvantages, the 'form herein disclosed being a preferredembodiment for the vpurpose of illustrating theinvention.

The'invention is hereby claimed as follows:

1. An inert grid comprising a foraminous screen oi beryllium.

2. An inert grid comprising an alloy of beryllium with platinum.

3. An inert grid comprising a network of beryllium wire.

4. An inert grid comprising an alloy of beryllium with platinum forming a foraminous screen.

5. An inert grid comprising a network of wires formed of anvalloy of beryllium with platinum.

' ZED J. ATLEE.

REFERENCES CITED The following references are of record in the file of this patent;

UN STATES PATENTS Number Name y Date 1,180,614 Simpson Apr. 25, 1916 1,981,620 Giard Nov. y20, 1934 1,989,954 VanGessel Feb. 5, 1935 2,358,200 Atlee Sept. 12,1944 2,368,060 `Wooten Jan. 23, 1945 FOREIGN PATENTS Number Country Date Denmark '-.f Feb. 3, 1936 

